Hydraulic engines are widely used today to transform mechanical energy into usable motion. In some commonly known conventional internal combustion engines, reciprocating combustion pistons are mechanically connected to reciprocating hydraulic pistons. Expanding combustion gases drive the reciprocating combustion pistons causing reciprocating hydraulic pistons to squeeze hydraulic fluid thereby producing a supply of pressurized hydraulic fluid. One such prior art hydraulic engine is shown in U.S. Pat. No. 5,167,292 to Moiroux et al. Moiroux's engine includes a pair of combustion pistons linked through connecting rods to a pivoted lever arm. The lever arm in turn attaches to a pair of hydraulic pistons so that the reciprocation of the combustion pistons reciprocates the hydraulic pistons thereby producing a supply of pressurized hydraulic fluid.
One of the drawbacks of this type of prior art hydraulic engine is large size, which makes it unsuitable for applications such as powering a vehicle. Accordingly, there is a need for a hydraulic engine of compact size and one that does not require the costly, complex transmissions of conventional internal combustion engines.
Another drawback of prior art engines is the problem posed by crank angle. Typically, an internal combustion engine uses a crankshaft to convert lateral piston movement to axial rotation. In conventional engines, this conversion is performed by a crankshaft. However, because of the crank angle, only a portion of the force generated at the piston face is applied to the crankshaft, the remainder being applied to the cylinder wall. The effect of “piston slap”, as it is known, is undesirable.
It is an object of the present invention to overcome one or more of the above-described drawbacks and/or disadvantages of the prior art.